Production lines inspect semiconductor substrates and membrane substrates for defects on the surfaces in order to maintain and improve the product yield. Defect inspection technologies of the related art are known as Japanese Unexamined Patent Application Publication No. Hei9 (1997)-304289, Japanese Unexamined Patent Application Publication No. 2006-201179, and U.S. Patent Application Publication No. 2006/0256325. These technologies condense illuminating light on a specimen surface in an area of several tens of micrometers to detect micro defects. The technologies condense and detect scattering light from a defect and inspect an area ranging from several tens of nanometers to several micrometers for defects. The technologies rotate and translate a stage supporting a specimen (test object) so that an illuminating spot helically scans the specimen surface to inspect the entire specimen surface.
The technologies described in Japanese Unexamined Patent Application Publication No. Hei9 (1997)-304289 and Japanese Unexamined Patent Application Publication No. 2006-201179 detect a component emitted at a high angle and a component emitted at a low angle in the scattering light from a defect and categorize a defect type based on a ratio.
The technology described in Japanese Unexamined Patent Application Publication No. 2006-201179 calculates the size of a detected defect based on the intensity of scattering light from the defect.
To reduce thermal damage on a specimen, the technology described in U.S. Patent Application Publication No. 2006/0256325 controls the illuminating light power, the speed to scan an illuminating spot, or the illuminating spot size while inspecting a test surface. More specifically, the technology assumes that the thermal damage given to a specimen is found by multiplying the illumination power density to be applied and the irradiation time together. While keeping the thermal damage below a specified value, the technology varies the illuminating light power, the speed to scan an illuminating spot, or the illuminating spot size according to radial positions on the specimen being scanned.
The technology described in U.S. Pat. No. 6,608,676 inspects the entire specimen surface in a short period of time by illuminating a wide range of specimen using a long Gaussian beam in one direction and detecting an illuminated area at a time using a detector such as a CCD including multiple pixels.
The technology described in U.S. Pat. No. 7,385,688 concerns the oblique-incidence illumination and uses an aspherical lens and a diffractive optical element to shape the illuminating light so as to position multiple illuminating spots on a test surface.
The technology described in Japanese Unexamined Patent Application Publication No. 2006-330007 forms an image at a slant in a two-dimensional area on the test surface and integrates and detects a detection signal using a TDI image sensor.